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Geomembranes (GMs) are widely used in hydraulic applications. Unfortunately, some additives contained in GMs are extracted upon prolonged contact with water or soil. Depending on their chemical nature, additives contained within GMs or degradation products thereof may affect natural ecosystems. To better understand this effect, the present study evaluates the potential impact of additives extracted from GMs that are commonly used in hydraulic applications. The approach consists of identifying additives contained in both unaged and aged high-density polyethylene and polypropylene GMs. Next, these GMs are immersed for various time intervals at 80, 55, and 25 °C in aqueous solutions (pH 4 and 7), and the chemical composition of the resulting solution is analyzed by ultraviolet absorbance spectroscopy. In addition, the effect of these solutions containing the GM extracts on the growth of Chlorella vulgaris and on the swimming of Daphnia sp . is studied. The first few days of exposure to the extracted molecules negatively impact C. vulgaris growth and Daphnia sp. swimming behavior. However, after prolonged exposure, the impact is reversed and microalgae growth is stimulated instead. This result may be related to the change of the nature of the molecules detected by UV spectroscopy. [ABSTRACT FROM AUTHOR]

Herbicides are widely used to control weeds and maximize crop growth. Because of agricultural runoff, these chemicals are potentially hazardous to aquatic wildlife. However, their ecotoxicity and resulting disturbance in individual performance remain scarcely documented in freshwater crustaceans. This study aimed to screen the potential toxicity of currently used herbicides in the ecosystem engineer Gammarus fossarum using multi-level biomarkers. In microcosms, gammarids were exposed for 72 h to 12 herbicides individually (quinmerac, mesotrione, bentazone, isoproturon, chlortoluron, metazachlor, chloridazone, diflufenican, flufenacet, aclonifen, prosulfocarb and metolachlor) at a field-realistic concentration (i.e. 10 μg/L). The sublethal effects were assessed by monitoring several biochemical, physiological and behavioural traits. In exposed gammarids, alterations in behavioural activities were observed, i.e. increased locomotion and respiration as a general trend. Moreover, biochemical biomarkers suggested herbicide-dependent disruptions in moulting, antioxidant responses and cell integrity. Integrating multi-metric variations through statistical analyses allowed us to identify herbicide clusters likely to trigger common sets of biological responses. Depressed antioxidant defence at the cell level and impaired respiration at the individual level were the predominant toxic effects of herbicides, related to their hydrophobic feature. Furthermore, establishing relationships between sublethal alterations in gammarids and acute lethality or chronic toxicity values defined for regulatory purposes supports the relevance of these alterations as early warnings of toxicity. Our findings demonstrate that currently used herbicides have unexpected toxicological effects in a non-target wild animal, with possible long-term alterations in population dynamics and associated ecological functions, which constitute promising diagnostic tools for risk assessment in agricultural areas. [Display omitted] • A wild aquatic species is exposed to herbicides at realistic exposure levels. • Herbicides elicit adverse effects at different organizational levels in gammarids. • Behaviour, individual performances and cell functions are altered by herbicides. • These multi-level responses evidence the harmful feature of herbicides on wildlife. • Such sublethal changes are thus promising early endpoints for risk assessment. [ABSTRACT FROM AUTHOR]

In this study isotopic tracing using 13 C labelled pentachlorophenol (PCP) and 2,4,6-trichlorophenol (2,4,6-TCP) is proposed as a tool to distinguish the loss of PCP and 2,4,6-TCP due to biodegradation from other physical processes. This isotopic approach was applied to accurately assess in situ PCP and 2,4,6-TCP degradation under methanogenic conditions in several microcosms made up of household waste. These microcosms were incubated in anaerobic conditions at 35 °C (mesophilic) and 55 °C (thermophilic) without agitation. The volume of biogas produced (CH 4 and CO 2 ), was followed for a period of 130 days. At this stage of stable methanogenesis, 13 C 6 -PCP and 13 C 6 -2,4,6-TCP were introduced anaerobically in microcosms and its monitoring at mesophilic and thermophilic conditions was performed in parallel by gas chromatography mass spectrometry (GC–MS) and gas chromatography isotope-ratio mass spectrometry (GC–IRMS). This study proved the almost total dechlorination of bioavailable PCP and 2,4,6-TCP into 4-CP at 35 °C. Nevertheless, high rate adsorption in particular materials of the two compounds was observed. Furthermore, Carbon-13 Nuclear Magnetic Resonance ( 13 C-NMR) Spectroscopy analysis of 13 C labelled 2,4,6-TCP mesophilic incubations showed the partial mineralization of 4-CP at 35 °C to acetate and then to HCO 3− . Consequently, NMR results confirm the biogas isotopic results indicating the mineralization of 13 C labelled 2,4,6-TCP into 13 C (CH 4 and CO 2 ). Concerning 13 C labelled PCP mesophilic incubations, the isotopic composition of the biogas still natural until the day 262. In contrast, no dechlorination was observed at 55 °C. Thus PCP and 2,4,6-TCP were persistent in thermophilic conditions. [ABSTRACT FROM AUTHOR]